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Youre preparing your next
case and have lined up your medical experts. You have poster exhibits of key documents,
and have even prepared a realistic 3D computer animation illustrating your experts
testimony. For many cases, youre set. In others, you still need something to
illustrate that one key issue that is critical for the jury to understand. You need a
physical model of a particular part of the affected anatomy that your expert can point to
or manipulate, and the jury can hold and view in great detail. With new technology, you
can have real, physical models of practically any object represented or created in 3D
(three-dimensions) by a computer. The uses in and out of the courtroom are endless.

The process is called
Stereolithography. The condensed technical definition states that a computer directed
ultra-violet laser solidifies photosensitive polymer in cross-sections, layer-upon-layer,
to produce a physical plastic-based model. The fundamental process is based on the fact
that liquid can be changed instantaneously into a solid state when exposed to ultraviolet
radiation, much as silver changes state in normal photography film when exposed to visible
light radiation.

Medical
Applications of Stereolithography

One way this technology is
currently being used is in the medical field. Surgeons now use 3D physical models created
with stereolithography from that same 2D data. Previously, they relied on 2D
(two-dimensional) CT or MRI data to view affected anatomy in preparation for complex
surgeries.

Through the process of preparing
the computer file with the data to be imaged, the areas of anatomical interest (bone,
tumor, soft tissue, or other) are identified. The model is then created in layers of only
0.006 of an inch. Different tissues (e.g. tumor) can be clearly defined by applying a
different color to the area. The models can also be transparent, so it is possible to
visualize structures within structures.

The majority of the work
generated in this fashion is for the surgical fields of craniofacial reconstruction,
neuro-surgery, and orthopedic surgery. Typical applications are for surgical
reconstruction following severe trauma, tumor, gunshot wounds, birth defect, or revision
of previous surgery. One of the key considerations to utilizing stereolithography, is that
the final model can only be as accurate as the data provided. There are many factors that
determine quality output. Consulting with a firm specializing in stereolithography can
identify the areas of importance.

Forensic Applications of Stereolithography

Interpreting data from MRIs and
CTs are just two ways of taking 2D information and creating real 3D models. Since the
technology is also used for prototyping in the manufacturing and engineering fields, the
process readily accepts computer aided drafting (CAD) files. Essentially, models
pertaining to construction defects or faulty engineering resulting in product defects, can
just as easily be created. Because the techniques used in forensic animations of product
liability, accident reconstruction and other areas are so closely related to the CAD
process, virtually all models used in forensic animations can be converted to 3D models as
well.

Imagine the big picture and
the possibilities. There are techniques that allow accurate scanning of physical
objects, such as defective products or equipment, for creation of 3D computer files. These
computer files are used to create 3D animations depicting the events surrounding a product
failure or other situation.

Stereolithography adds another,
real world, dimension to the presentation of evidence. The same information used in
creating the animation can be used to create complimentary 3D models for use as exhibits
in trial. An effective presentation can now include video and or animation or the events,
enhanced by a physical model used to isolate important areas for further discussion with
expert witnesses, and to educate and persuade the jury.

Cost of Creating Stereolithography Models

The cost is greatly affected by
the subject and its complexity. For example, a medical model of a human skull is roughly
$3,000. Costs can range from a few hundred dollars to a few thousand. The relatively low
cost puts stereolithography models in the same category as large poster exhibits used
every day in trials throughout the country. The process clearly breaks the 2D to 3D
barrier for presentation of evidence.

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